Tubular push rod and method of making same



Aug. 4, 1959 E. E. ETZLER TUBULAR PUSH ROD AND METHOD OF MAKING SAME Filed Nov. 8, 1957 INVENTOR. EL Mae E, E121. 52

ATTORNEYS TUBULAR PUSH ROD AND METHOD OF MAKING SAME Elmer Etzler, Winchester, Ky., assign'or to Bundy Tubing Company, Detroit, Mich., a corporation of Michigan Application' November 8, 1957, Serial No. 695,384 12- Claims'. (Cl. 1'23-'- -90) push rod of this invention may be used tointerkinds of ma'chines'. A good example of a use of the invention is a push rod for operatively connecting a valve lifter with a valve operating rocker aim in an internal combustion engine.

I The inventiongenerally contemplates making push rods by inserting an end piece into'each end of a tube and securing it in place with a portion of the e'nd'p'iece projectin'g' out of the end of the tube'to engage a cam follower, rocker arm or other mechanism. It is desirable to" use tubing which is formed by transversely rolling strip stock to tubular form and welding or brazing the interfacing portions of the stock together;

This kind of tubing is relatively inexpensive as compared to-seamless tubing, and it has the necessary structural strength; Heretofore, it has not been economically advantageous to' use this kind of tubing because the usual internal irregularities at the longitudinal seain area of the tubing prevent centering the insert in the tube with the accuracy required in push rod construction. Reducing or removing the seam irregularities such as-by scarfing, ream-ing, or mandrel drawing the tubing and the necessity ofsubse'quently' internally gauging the tubing increases its'c'ost-objectionably.

Anobjectof this invention is topr'o vide an improved economical method of making tubular push rods of the type described.

The invention is carried out generally by deforming the end portions of the tube tojprovide at three or more circ'umferentially spaced location's protrusionswhich project generally radially into the tube, a distance greater than the inward extent of any irregularities at the seam area. The protrusions engage the insert and center it within the tubeend. One form or"- the invention is shown in'the accompanying drawings:

Figure 1 is a View partly in elevationand partly in section illustrating a push rod according to this invention in use.

Figure 2 is an enlarged fragmentary view of one end of the push rod with parts shown in phantom toillustrate structure.

, connect a large variety of movable members in various I 2,897,805 Patented Aug. 4, 1959 2 ice 2. one arm 19 operably engaged with a valve 20 and with another arm 21 on the opposite side of shaft 18 engaged by the push rod. Valve 26 is shown as being spring returned by a spring 22. Arm 21 of rocker 12 and the upper portion of litter 11 are recessed as at 25 and 26 for receiving end pieces 27 of the push rod.

Push rod 10 is formed of a length of tube 30' which is formed by rolling flat strip stock transversely to tubular form, and securing the interfacing portions of the stock together by a fused metal connection such as-brazing or welding. The tube thus has a longitudinal seam. The tube may have a single wall thickness and the interfacing portions of the stock forming the tube may be butt welded as illustrated diagrammatically at 31- in Figures 3 and 4. The welding may be accomplished byany suitable means such as by electric resistance welding or arc welding. In some instances the joint may be brazed; Suitable tubing may also be provided by transversely rolling the strip stock through ab'out720" to form pluralwall tubing with the interfaces brazed together as disclosed for example in Woeller 2,292,810, dated Aug. 11, 1942 and entitled Method and Apparatus for Making Tube.

For purposes of illustration, it may be assumed that the tubular stock 32, Figure 3, from which the push rod of this invention is made, has a single Wall thickness and that the side edges are butt welded by electric resistance. External and internal beads or flashing formed by the welding are illustrated at 33 and 34. The end portions of tubing 32 are conditioned for receiving end pieces 27 by deforming the walls of the end portions radially inwardly at at least three circumterentially spaced locations to provide inward projections 36. which are shown in somewhat exaggerated form. These projections may be conveniently provided by fluting' the tubing as at 37 along axially extending lines by dies which are secured in a press and advanced axially over the endof the tube. Where the flutes are formed without supporting the tube interiorly by means of a mandrel, the tube may be somewhat flattened in the vicinity of the flutes as illustrated in Figure 4.

End pieces 2'7 may be applied to the fluted tube ends by inserting a cylindrical portion 4% into the'tube so that it is engaged by inward projections 36 formed by the flutes. Cylindrical insert may have a taper end 41 to facilitate its entry into the tube end. End piece 27 has a rounded end portion 42 which projects out of the tube seats on the end face of the tube, Figure 2, toproperly tion 42 relatively to the tubing.

' Figure 3 is an enlarged view of an end of a piece of tubing before it isconditioned for receiving aninsert.

Figure 4 is a view similar to Figure 3 illustrating the end of apiece of tube after it is conditioned for receiving an insert.

Figure 5 is a view similar to' Figure 4 illustrating the end of-the tube after an insert has been inserted therein. Figure 6 is a fragmentary view" of an endportion of a piece of tubing having a different type of insert.

Figure 7 is a view of a modified piece of tubing. Shown in Figure 1 is a push rod- 10, according to this invention, op'eiably interconnecting a valve lifter 1'1 and a valve-actuating rocker 12. Litter 11 is raised and lowered by a cam1'3 on a cam sha'ft14 and the lifter moves in a guide 1-5 which may be formed in an engine block 16. Rocker 12 is rockably mounted ona shaft 18*wit-h during the fiuting process projections 36 should be pressed position portion 42 longitudinally of the tube. Projections 36 extend toward the tube interior radially a substantially equal distance and engage cylindrical insert portion 40' snugly for centering the insert and end por-1 Projections 36- extend inwardly a distance greater than flash 34' at the seam area so that the insert is out of contact with the flash.- Thus the presence of hash 34 does not aiiect centering of insert 40 or end portion 42 and it is unnecessary to remove or reduce the size of the flash.

'Ilhe radially inward extent of projections 36 need not be closely controlled since the only requirement is that they project inwardly far enough to engage cylindrical portion 441 snugly and hold it spaced from flash 34 If further inwardly than necessary, the metal of the tube end will be merely expanded back out when cylindrical insert 40 is driven into the tube end, compare Figures 4- and 5. After cylindrical insert 40 has been positioned within the tube end, it may be permanently secured into place such as byspot welding 44 at a location" where projection 36 engages the insert. The push rod is now complete.

End pieces 27 are properly centered and longitudinally positioned so that outwardly projecting portions 42 are located for engaging rocker arm 21 and valve lifter 11. Inner flash 34 at the seam area need not be reduced or removed. Since projections 36 need not extend into the tubing to any accurately controlled extent, no gauging of the tube interior is necessary during manufacture. Thus the process of mounting end pieces 27 on the tube to complete the push rod is rapid, economical and effective.

Figure 6 illustrates a push rod ltla similar to push rod except that a different type of end piece 27a is illustrated having a recess 45 at its outwardly projecting end rather than a ball 42 for engaging adjacent mechanism.

Figure 7 illustrates a modified form of push rod 50 similar to the form shown in Figure 1 except that tube 51 has flutes 52 extending through its entire length rather than just a short distance from its ends. This modification enables the tube manufacturer to provide fluted tubular stock in relatively long lengths. The push rod manufacturer may cut the tube to various desired shorter lengths for completion by addition thereto of end pieces 27, as described.

I claim:

1. The method of making a push rod which comprises, conditioning an end portion of an open-ended tubular element for receiving an insert in substantially centered relation on a predetermined center therein by deforming the wall of said tubular element to provide said end portion with generally axially inwardly extending projections at at least three circumferentially spaced locations, and securing an insert in the conditioned end portion of the tubular element so that said insert is centeringly engaged by said projections and so that the apposed portions of the tube interior and insert exterior extending circumferentially between said projections are spaced apart, while leaving a part of said insert projecting out of said end portion for operative engagement with other mechanism.

2. The method of making a push rod which comprises, conditioning an end portion of an open-ended tubular element for receiving an insert in substantially centered relation therein by deforming the wall of said tubular element to provide said end portion with axially elongate, generally radially equally inwardly extending projections at at least three circumferentially spaced locations, securing a generally cylindrical portion of an insert in the conditioned end portion of the tubular element so that said cylindrical portion is centeringly engaged by said projections and so that the apposed portions of the tube interior and insert exterior extending circumferentially between said projections are spaced apart, while leaving a part of said insert projecting out of said end portion for operative engagement with other mechanism.

3. The method defined in claim 2 wherein said elongate projections extend axially from an extreme end of the tubular element through a distance which is small relative to the length of said tubular element.

' 4. The method defined in claim 2 wherein said elongate projections extend through substantially the entire length of said tubular element.

5. The method of making a push rod which comprises providing an open-ended tube having a longitudinal seam, conditioning an end portion of said tube for receiving an insert by deforming the wall of said tube to provide said projections and so that the portions of said insert extending circumferentially between said projections are spaced from the tube interior and clear said irregularities, while leaving said bearing surface projecting out of said end portion of the tube.

6. The method of making a push rod which comprises, forming a tube :by rolling a strip of metal transversely to tubular form and bringing edge portions thereof together at a longitudinal seam area, joining interfacing portions of the metal strip by a fused metal connection,

conditioning an end portion of the tube for receiving an insert by deforming the wall of said tube to provide inwardly extending projections at at least three circumferentially spaced locations with said projections extending inwardly a distance greater than the inward extent of irregularities at the longitudinal seam, providing an end piece having one end portion forming an insert and another end portion forming a bearing surface adapted for operative engagement with other mechanism, and securing said insert in said conditioned end portion of the tube so that said insert is centeringly engaged by said projections and so that the portions of said insert extending circumferentially between said projections are spaced from the tube interior and clear said irregularities, while leaving said bearing surface projecting out of said end portion of the tube.

7. The method of making push rod which comprises, rolling metal strip stock transversely to tubular form with its edge portions in apposed relation, welding said edge portions together in a longitudinal seam, conditioning an end portion of the tube thus formed for receiving an insert by deforming the wall of said tube to provide inwardly extending projections at at least three circumferentially spaced locations with said projections extending inwardly a distance greater than the inward extent of interior flash formed incidental to the welding of said seam, providing an end piece having one end portion forming an insert and having another end portion forming a bearing surface adapted for operative engagement with other mechanism, and, without otherwise conditioning the interior of said tube, securing said insert in said conditioned end portion of the tube so that said insert is centeringly engaged by said projections and so that the portions of said insert extending circumferentially between said projections are spaced from the tube interior and clear said interior flash, while leaving said bearing surface projecting out of said end portion of the tube.

8. A tubular push rod comprising, a length of tube having open end portions, each end portion having at least three generally radially inward projections at circumferentially spaced locations, a member disposed within each of said end portions and being engaged by said projections so that said member is substantially centered on a predetermined center within said end portion, the apposed portions of said member and the tube interior extending circumferentially between said projections being spaced apart in a radial direction, said members projecting out of said end portions and being formed for operative engagement with other mechanism.

9. A tubular push rod comprising, a length of tube having a longitudinal seam and having open end portions, each end portion having at least three generally radially inward projections at circumferentially spaced locations, said projections extending inwardly a distance greater than the inward extent of irregularities in the seam area, a member disposed within each of said end portions, said member being engaged and substantially centered within said end portion by said projections, the apposed portions of said member and the tube interior extending circumferentially between said projections being spaced apart in a radial direction so that said member clears the irregularities at the seam area of said tube, said members projecting out of said end portions and being formed for operative engagement with other mechanism.

10. A tubular push rod comprising a length of tube having a longitudinal seam and having open end portions, each end portion having at least three axially elongate, generally radially inward projections at circumferentially spaced locations, said projections extending inwardly a distance greater than the inward extent of irregularities at the seam area of said tube, a generally cylindrical member disposed Within each of said end portions and being engaged by said projections so that said member is substantially centered within said end portion, the apposed portions of said member and tube interior extending circumferentially between said projections being spaced apart in a radial direction so that said member clears the irregularities at the seam area of said tube,

said members having portions projecting out of said end 15 ,708,

References Cited in the file of this patent UNITED STATES PATENTS Linendoll Apr. 26, 1921 Jenny et a1. Oct. 9, 1945 Dunn May 10, 1955 

